The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A stop-start vehicle and a hybrid electric vehicle (HEV) may each include an internal combustion engine (ICE), a transmission and one or more electric motors and a control module. The stop-start vehicle and the HEV may shut down (deactivate) an ICE, for example, to reduce the amount of time the ICE is idling. This improves fuel economy and reduces emissions. The ICE may be shut down when vehicle speed is less than a threshold.
In a stop-start system and in a HEV system an ICE may be shut down and/or transitioned to an at rest state (i.e. engine speed is equal to 0 revolutions/second). The ICE may be automatically started, for example, when an accelerator pedal is actuated.
A transmission of a stop-start vehicle system and of a HEV system may include a torque converter that is connected to an ICE. A clutch of the torque converter and, for example, a first gear of the transmission may be engaged prior to startup of the ICE. With the clutch and first gear engaged the vehicle can begin to move forward, as long as the ICE produces torque. Although this can improve response time of vehicle launch of a stop-start vehicle system and a HEV, powertrain vibrations during startup can result due to an increase in speed of the ICE and load of the transmission on the ICE.